Hammer mill construction



W. E. BERLING HAMMER MILL CONSTRUCTION Oct. 28,1958

2 Sheets-Sheet 1 Filed July 22, 1957 INVENTOR. MAL/HM E. PERI/N c.

'oci. 28, 1958 Filed July 22, 1957 w. E. BERLING 2,858,082

HAMMER MILL CONSTRUCTION 2 Sheets-Sheet 2 INVENTOR. MAL/0n I. final/v62 United States Patent C) HAMMER MILL CONSTRUCTION William E. Berling, Indianapolis, Ind. Application July 22, 1957, Serial No. 673,515

3 Claims. (Cl. 241-486) This invention relates generally to hammer mills, and in particular to a hammer mill in which the texture and fineness of the grind may be accurately controlled.

In the past, in order to change the degree of fineness of the material ground by conventional hammer mills, it has been necessary to interchange the screen mesh elements through which the material to be ground is pounded or forced in conventional hammer mill operation. This time consuming interchange of screens required shutdown of the mill and necessitated maintaining on hand a variety of screens having difierent mesh sizes.

It is the primary object of this invention to provide an improved hammer mill in which both the rate of admission of material into the mill, the fineness of the grind, and the uniformity of texture of the material processed by the mill can all be readily adjusted by an operator positioned on the operating floor above the mill, without the changing of screens or the like.

A further object of the present invention is to provide an improved hammer mill in which the fineness of grind and the uniformity of texture of the material processed can be accurately controlled by a single adjustment. This adjustment varies the area of a flexible grinding plate which is swept by the moving hammer elements and simultaneously determines the size of the outlet opening in the grinding chamber.

A further object of the present invention is to provide ahammer mill in which the material to be processed is held in suspension by air drawn through the mill and all of the material is maintained in contact with the hammer elements for the same length of time.

A further object of the present invention is to provide an improved hammer mill in which a feed gate member is adjustably positioned to determine the rate of admission ofmaterial into the grinding chamber and the degree of initial breakdown of material admitted into the grinding chamber.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

Fig. l is a side view of a hammer mill embodying the present invention, but omitting certain of the parts for clarification of the disclosure.

Fig. 2 is an end view of the apparatus shown in Fig. l .with portions thereof broken away to more clearly show the operation of the mill.

Fig. 3 is a top plan view of a portion of the apparatus shown in Fig. 2.

Fig. 4 is a schematic view in a flat rangement of the hammer elements.

Referring initially to Figs. 1 and 2, a structural steel base It supports a housing having side plates Ill and 12, end plates 13 and id, and a base plate 15.

The end plates are curved across their upper margin and are widened adjacent their line of juncture with the side plates, the slot formed by the offset mounting of side plate 12 relative to the end plates being closed by plane of the ar 2,858,082 Patented Oct. 28, 1958 a member 12a bolted to the side plate 12 and having a curved lower section providing a streamlined surface.

Each of the end plates carries a member 17 providing a curved track or groove 13 and terminating in a curved plate 19 which extends between the end plates and across the housing. An opposing curved plate 21 is supported by each of the end plates and extends across the housing, and is ofi'set from the side plate 11 to provide a slot or opening 22. The opening 22 provides access into the housing for a flexible grinding plate made up of a series of metal strips 23, hardened by heat-treating and joined on their under face by means of the pivotally linked chain 24.

The upper faces of the metal strips each carry a generally V-shaped riser or boss 23a, as may best be seen in Fig. 3, providing a grinding surface. The ends of the metal strips are accommodated within the grooves 18 carried by the end plates, and the terminal series of strips are supported in inclined position outside the opening 22 by means of a bracket 26 carried on the upper margin of the side plate 11.

As indicated at 26, a shaft extends across the housing and is journaled for rotation therein. The shaft has keyed thereto two spaced sprockets 27 and. 28 which, as may best be seen in Fig. 2, engage the chain which joins the metal strips 23. Outboard of the housing the shaft also carries a sprocket 29 which accommodates a chain 31, extending to a drive sprocket 32 keyed to a shaft 33. The shaft 33 may be rotated by means of a hand crank 34 and may be suitably mounted remotely from the hammer mill, as for example, on the operating floor above the mill.

From the foregoing it will be evident that the parts so far described provide a housing of generally involute configuration, enclosing a grinding chamber 16 which has an inlet opening 36 and an outlet opening 37. The size of the outlet opening will depend upon the degree of advancement of the flexible grinding plate, formed by the strips 23, into the grooves 18, the position of the grinding plate being adjustably variable by rotation of the sprockets and through manipulation of the hand crank.

A main drive shaft 41 is journaled in bearing members 42 supported on the housing, and extends centrally across the grinding chamber. At one end the shaft is' coupled to a driving means, such as an electric motor 43, suitably mounted upon the base structure. Keyed to the shafts are a longitudinally spaced series of plates or discs 44, each plate being provided with spaced openings 46 adjacent its periphery.

The openings in the plates are longitudinally aligned and have journaled therein rods or shafts 47. Pivotally mounted upon the rods, between the discs 44, are a plurality of grinding hammers 48 which, upon rotation of the shaft 41 are adapted to-sweep over that portion of the surface of the flexible grinding plate which is inserted within the housing.

As may best be seen in Fig. 4, the hammers are grouped in staggered relation so as to present a series of concentric, generally V-shaped impact surfaces to the material being processed as the rotation of the drive shaft proceeds.

A feed gate member is movably mounted within the upper part of the housing and includes a gate or front plate 49 and, rigidly secured thereto, a curved grinding plate 51 having spaced risers or bosses 52 on its under face. The risers have a configuration similar to the risers carried by the strips 23. The front plant extends freely through an opening 53 in the housing and the assembly is supported and movably positioned by means of a worm shaft 54 extending from the feed gate member and threaded through a bearing member 56 mounted upon the exterior of the housing. The worm shaft may extend above the housing to a point adjacent the hand crank 34 so that it may be rotated by means of the handle 57 by an operator stationed on the operating floor above the mill.

It will be understood that the front plate 49 extends across the inlet opening to the grinding chamber, and that the position of the grinding plate 51 with relation to the hammer tips, and the effective size of the inlet opening to the grinding chamber may be simultaneously varied by adjustably rotating the worm shaft 54.

The means for directing the material to be processed into the grinding chamber comprises a feed apron or table 58 pivotally supported on the housing at $9. For the sake of clarity, this feed apron and associated parts are notshown in Fig. 1.

On its under face the apron carries a member at) slotted to receive a clamping bolt 61 carried by one end of a brace 62 which has its other end pivotaliy mounted on the housing at 63. This construction permits swinging the table about its hinged connection to the housing and fixing it in a position determined by the character of the material to be transmitted to the grinding chamber.

The means for drawing air through the mill includes a blower 64, which may be of the centrifugal type, rotated by the shaft 41 and supported by any suitable means, such as brackets (not shown) extending between the blower housing and the lower portion of the end plate 13. p

The inlet 66 of the fan communicates with the outlet opening of the grinding chamber by means of a duct 67 which is secured across a rectangular opening 68 in the side plate 12 just below the member 12a. An opening 69 provides an air inlet for the grinding chamber and is covered by a perforated, hinged metal door '71. The outlet of the blower may be connected to a coupling 72 which may be suitably adapted to deliver the processed material for bagging or other disposal.

In operation, with the shaft 41 rotating clockwise (as viewed in Fig. 2) and with the blower inducing a flow of air into the inlet opening 69, through the grinding chamber, and through the outlet opening 37, material to be ground may be dispensed from the feed apron to the grinding chamber inlet opening 36. The material will be initially broken up between the hammer tips and the plate 52, and as it proceeds through the grinding chamber, will be further ground between the hammers and the flexible grinding plate.

As the material leaves the area adjacent the upper plate 52 it will be entrained by the air passing through the grinding chamber. In passage along the surface of the flexible grinding plate, the material will be heid in suspension in the air stream as the grinding operation is completed by the hammers. The air the entrained ground material will leave the grinding chamher through the opening 37 and will be drawn through the duct 67 and delivered at the outlet coupling 72 by the blower.

Thegenerally inclined or V-shaped configuration of the positional arrangement of the hammers, together with the configuration of the V-shaped risers or bosses on each of the strips 23 assure that the grinding operation may proceed with a relatively uniform application of the grinding force to the material as the hammers sweep the surface of the flexible grinding plate.

It will be noted that the position of the front plate 49 determines the rate of flow of material into the grinding chamber. With the positioning of the front plate, the upper grinding plate 51 is also positioned to determine the amount of initial breakdown of the material admitted'into the grinding chamber.

This adjustment may be set so that the rate of admission of material to the grinding chamber and the initial breakdown of the material is such that the electric motor driving the shaft 41 is not overloaded. The initial break- Cat 4 down of the material provided by the plate 51 has the further characteristic of providing a more even and uniform grind of the finished product.

Since the size of the grinding chamber outlet opening 37 is determined by the position of the flexible grinding plate, it will be evident that as the flexible grinding plate is advanced into the accommodating grooves, the volume of air drawn through the grinding chamber per unit of time will be reduced.

This reduction of the volume of air flowing through the g'fc, chamber tends to retain the material within the chamber for a longer time, thereby resulting in a finer grind. The additional area of the flexible grinding plate swept by the hammers as the plate is advanced across the opening 37 provides an improved uniformity of texture of the ground material. It will thus be evident that by advancing the flexible grinding plate by means of the adjusting hand crank 34 the grind may be made finer, by withdrawing the flexible plate the grind may be made more coarse.

The arrangement of parts described above provides a hammer mill in which the fineness of grind may be adjusted conveniently without the changing of screens or mesh plates, and in which the adjustably positioned grinding plate varies the length of time the material to be processed is in impact suspension thereby attaining a uniformity in texture of the finished product which is unknown in screen type mills. Since the air flow induced by the blower is directly across the grinding plates and not turbulated through a screen, as in conventional hammer mills, the prior requirements for the blower to produce a given output are considerably reduced.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that it is intended that all changes and modifications that come within the spirit of the invention and the scope of the claim are also to be protected.

he invention ciairned is:

1. A hammer mill comprising a housing having a generally involute' configuration providing an inlet opening into the housing for material to be processed, an outlet opening formed in the base of said housing, a grinding plate slidably mounted within the housing providing an adjustable closure for the outlet opening, said plate being formed of pivotally joined sections so as to adapt itself to the curved surface of the housing, hammer elements movably mounted within the housing and adapted to sweep the adjacent area of the grinding plate for grinding the material passing therebetween, a feed gate member movably mounted across said inlet opening for controlling the admission of material into the housing, manual means accessible exteriorly of said housing for adjustably positioning said grinding plate and said feed gate member, and air moving means adapted to draw air through said housing for entraining the processed material and delivering it through said outlet opening.

2. A hammer mill comprising a housing having a generally involute configuration providing an inlet opening into the housing for material to be processed, an outlet opening formed in the base of said housing, a grinding plate slidably mounted within the housing providing an adjustable closure for the outlet opening, said plate being for or pivotaliy joined sections so as to adapt itself to the curved surface of the housing, hammer elements movably mounted Within the housing and adapted to sweep the adjacent area of the grinding plate for grinding the material passing thcrebetween, a feed gate member movably mounted across said inlet opening for controlling the admission of material into the housing, and manual means accessible exteriorly of said housing for adjustably positioning said grinding plate and said feed gate member.

3. A hammer mill comprising a housing having a gen erally involute configuration providing an inlet opening into the housing for material to be processed, an outlet opening formed in the base of said housing, a grinding plate slidably mounted within the housing providing an adjustable closure for the outlet opening, said plate being formed of pivotally joined sections so as to adapt itself to the curved surface of the housing, hammer elements movably mounted within the housing and adapted to sweep the adjacent area of the grinding plate for grinding the material passing therebetween, and manual means accessible exteriorly of said housing for adjustably positioning said grinding plate.

References Cited in the file of this patent UNITED STATES PATENTS Williams June 6, 1922 Nelson May 10, 1927 Sedberry Feb. 14, 1928 Gately June 24, 1930 Calhoun Jan. 5, 1932 Hazle Apr. 6, 1937 Sheldon Aug. 23, 1938 Mankofi May 16, 1939 Korum Aug. 4, 1942 

